This application relates to a unique hub cap used in wheel end assembly for a tire inflation system. The hub cap includes an internal passageway for routing air from an air supply to the tire.
Tire inflation systems are used on vehicles to automatically supply air to tires when certain conditions are met. In a typical situation, the tire inflation system will automatically add air to a tire that becomes under-inflated during vehicle operation. These tire inflation systems include sensors and pressure regulators for monitoring the pressure in each of the vehicle's tires. When pressure in a tire drops below a predetermined level, the system automatically supplies air to the tire until a desire pressure is achieved.
Some systems include check valves that allow air flow in only one direction, i.e., allow air to flow from the air supply to the tire, so that unwanted tire deflation does not occur. Other systems include valves that control air flow into the tires and out of the tires so that several different tire pressures can be achieved depending upon the type of terrain. Usually the tire inflation systems also include an unloader valve that prevents air from being supplied to a tire if there is a blowout.
The tire inflation systems include an air tank that is mounted on the vehicle. Air is supplied from the tank to the tires in various manners. All of the systems must include a rotary connection that allows air to be supplied to the tires during rotation. Some systems include a rotary valve mounted on one end of the axle. Air is supplied from the tank to the interior of the axle. Air from inside the axle passes through the rotary valve and is conducted to the tires. Another system supplies air via a hub that is rotatable supported on the axle. Rotary seals are used to provide a sealed environment for air conduction.
Hub caps are mounted to the wheel hubs to enclose the wheel end and protect the wheel end components. Many tire inflation systems include fittings that extend outwardly beyond the hub cap. These fittings rotate with the wheel and serve as connections from the hub or axle air supply to the tires. Hoses extend from these fittings to valves on the tires. During vehicle operations, these fittings can be damaged because they extend beyond the hub cap and are exposed to external debris or other hazards. Under certain conditions, such as off-road duty cycles over rough terrain, the fittings can break off causing the tire inflation system to become inoperable.
Thus, it is desirable to have a wheel end assembly for a tire inflation system that does not require fittings extending beyond the hub cap and which provides an air passage from the air supply to the tires that is not easily damaged.